This is the Relative Name (Rn) of the EpUser object — the naming fragment that distinguishes this particular storage-endpoint login account from any siblings stored under the same parent endpoint. An admin uses the Rn to identify which specific account is which when a storage endpoint has more than one EpUser credential configured under it. If two accounts are configured for the same storage endpoint, their Rn values would differ (typically reflecting the username) even though they share the same parent path.